Computationally Efficient MPC for Modular Multilevel Matrix Converters Operating With Fixed Switching Frequency

Abstract

Modular multilevel matrix converters stand out for their performance in ac–ac high-power conversion. However, they require multiple control loops to govern the currents from both ac ports, the internal circulating currents, and the capacitor voltages. This article proposes a computationally efficient model predictive control (MPC) strategy based on a new converter modeling to exploit the phase-shifted pulsewidth modulation working principle fully, achieving four improvements: 1) control unification of both ac-ports currents, circulating currents, and capacitor voltages; 2) constrained optimization to safeguard the converter limits; 3) computational burden reduction and high scalability compared to standard MPC strategies; and 4) wide frequency operation with fast closed-loop transient responses, low harmonic distortion, and fixed switching frequency.

Keywords

• Direct ac-to-ac conversion
• model predictive control (MPC)
• modular multilevel matrix converter (M3C)
• phase shifted pulsewidth modulation (PS-PWM)
• sequential analysis
• triple-star bridge cells (TSBC)